virtio: properly validate address before accessing config
There are several several issues in the current checking: - The check was based on the minus of unsigned values which can overflow - It was done after .{set|get}_config() which can lead crash when config_len is zero since vdev->config is NULL Fix this by: - Validate the address in virtio_pci_config_{read|write}() before .{set|get}_config - Use addition instead minus to do the validation Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Petr Matousek <pmatouse@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Petr Matousek <pmatouse@redhat.com> Message-id: 1367905369-10765-1-git-send-email-jasowang@redhat.com Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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@ -568,10 +568,11 @@ uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr)
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VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
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uint8_t val;
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k->get_config(vdev, vdev->config);
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if (addr > (vdev->config_len - sizeof(val)))
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if (addr + sizeof(val) > vdev->config_len) {
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return (uint32_t)-1;
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}
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k->get_config(vdev, vdev->config);
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val = ldub_p(vdev->config + addr);
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return val;
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@ -582,10 +583,11 @@ uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr)
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VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
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uint16_t val;
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k->get_config(vdev, vdev->config);
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if (addr > (vdev->config_len - sizeof(val)))
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if (addr + sizeof(val) > vdev->config_len) {
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return (uint32_t)-1;
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}
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k->get_config(vdev, vdev->config);
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val = lduw_p(vdev->config + addr);
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return val;
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@ -596,10 +598,11 @@ uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr)
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VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
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uint32_t val;
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k->get_config(vdev, vdev->config);
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if (addr > (vdev->config_len - sizeof(val)))
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if (addr + sizeof(val) > vdev->config_len) {
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return (uint32_t)-1;
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}
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k->get_config(vdev, vdev->config);
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val = ldl_p(vdev->config + addr);
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return val;
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@ -610,8 +613,9 @@ void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data)
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VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
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uint8_t val = data;
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if (addr > (vdev->config_len - sizeof(val)))
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if (addr + sizeof(val) > vdev->config_len) {
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return;
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}
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stb_p(vdev->config + addr, val);
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@ -625,8 +629,9 @@ void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data)
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VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
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uint16_t val = data;
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if (addr > (vdev->config_len - sizeof(val)))
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if (addr + sizeof(val) > vdev->config_len) {
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return;
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}
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stw_p(vdev->config + addr, val);
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@ -640,8 +645,9 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)
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VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
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uint32_t val = data;
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if (addr > (vdev->config_len - sizeof(val)))
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if (addr + sizeof(val) > vdev->config_len) {
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return;
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}
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stl_p(vdev->config + addr, val);
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